The 42nd parallel north defining borders between states in the United States

Crossing the parallel in Girard, Pennsylvania

The parallel 42° north forms most of the New York-Pennsylvania border, although due to imperfect surveying in 1785–1786, this boundary wanders around on both sides of the true parallel. The area around the parallel in this region is known as the Twin Tiers.

The parallel 42° north passes through the southern end of Lake Michigan and Lake Erie. Part of the water boundary between Canada and the United States passes south of the 42nd parallel, and the southern tip of the Canadian province of Ontario just barely goes south of it - this is located at Point Pelee and Pelee Island.